Exactly how NOT to make a multicart for the C64

[Noizer]

Why you heroes of lost hardware dreams, don’t do something c o n s t r u c t i v e for this community?
http://sleepingelephant.com/ipw-web/bul ... 87#p108190
See first of my comment on that topic.
Since no one can prove the opposite, I declare this as the first and cheaper but more efficient way to play 8-bit mono or 4-bit stereo samples on Vicy. Challenge is open

[Gyro Gearloose]

Is there a way to simultaneously use an Eslapion product and a MCes product in a VIC-20?

I want to make this the goal of my life.

Someone has already tried it, here is the video of the experiment .... https://youtu.be/M2o2FRwn_hg?t=232

That reminds me of a Plenty Of Fish date I had once.

[Gyro Gearloose]

Why you heroes of lost hardware dreams, don’t do something c o n s t r u c t i v e for this community?
http://sleepingelephant.com/ipw-web/bul ... 87#p108190
See first of my comment on that topic.
Since no one can prove the opposite, I declare this as the first and cheaper but more efficient way to play 8-bit mono or 4-bit stereo samples on Vicy. Challenge is open

It's trivially easy to hook up a DAC to the VIC's user port. As a matter of fact, when I was in college studying electronics, many years ago, I brought my VIC with me. Instead of using the school's IBM-based computers I used my trusty VIC-20. Hooking up the user port to the Motorola MC1408 8 bit DAC was a fascinating experiment.

https://datasheetspdf.com/pdf-file/1243 ... a/MC1408/1

I remember using the MC1408 circuit to create a low frequency arbitrary signal generator. Using a few lines of BASIC I created a 256 byte table of values and I made the VIC cycle through it and output the values through the MC1408.

I also used this DAC to adjust the output voltage of a LM317 regulator. A few lines of BASIC to ask for the voltage and calculate the 8 bit value and I had a programmable power supply.

[eslapion]

Why you heroes of lost hardware dreams, don’t do something c o n s t r u c t i v e for this community?

Hey, buddy, I studied a couple of years at university, I created a couple of things for the VIC-20 and for the C64 and then here comes this guy who declares everything I learned is bullshit, everything I say is bullshit and everything I sell is crap.

Good luck indeed trying to do anything constructive under the circumstances.

http://sleepingelephant.com/ipw-web/bul ... 87#p108190
See first of my comment on that topic.
Since no one can prove the opposite, I declare this as the first and cheaper but more efficient way to play 8-bit mono or 4-bit stereo samples on Vicy. Challenge is open

You're not going to like me. I did that project back in 1984 and it has nothing to do with samples of any kind. It uses the shift register of the 6522 to play perfect square waves of various frequencies.

If that thing is able to play samples, I have no clue how.

[groepaz]

If that thing is able to play samples, I have no clue how.

All that studying left out DAC and PWM?

[MCeslapion]

If that thing is able to play samples, I have no clue how.

All that studying left out DAC and PWM?

I think Eslapion should do the DAC and MCes does the PWM. I want my Mum and Dad to work together. I don't like it when they fight.

[eslapion]

All that studying left out DAC and PWM?

I know perfectly well of DAC and PWM - I used both to make a uC controlled variable speed fan for aeronautics.

There's just none of either in the 2 pages of the VIC-20 P.R.G. mentioned in that specific thread.

I also used DAC and PWM to make a pure sine wave 12Vdc to 120Vac converter.

[groepaz]

Yet you cant imagine how to play samples with a shift register? I see.

[eslapion]

Yet you cant imagine how to play samples with a shift register? I see.

You could use it as a 1bit DAC, I suppose.

But that's completely besides the point. The basic program proposed in the PRG has one function only, play square waves of various frequencies and it does it magnificently. Where that thread turned to samples and DAC, it was no longer about what the OP tried to discuss.

[joshuadenmark]

Hi all

Please keep the debate friendly and constructive, do you even know how tiresome this is to follow?

In behalf of our community “please behave boys”.

[English Invader]

Please keep the debate friendly and constructive, do you even know how tiresome this is to follow?

No, because I haven't been following. I just switch off from topics that don't interest me and this one has been going around for years; gold plated connectors = good, non-gold plated connectors = bad. Got it.

eslapion is an old hand at making Commodore hardware accessories so I'll defer to his judgement on this one. My BB is still working fine after many years and he has nothing to prove here as far as I'm concerned. Case closed.

[Vic20-Ian]

Hi all

Please keep the debate friendly and constructive, do you even know how tiresome this is to follow?

In behalf of our community “please behave boys”.

Thanks for the more considerate moderation compared to the 20Q programming thread I was contributing to that was expunged in a digital version of Fahrenheit 451 with no warning

[MCeslapion]

eslapion is an old hand at making Commodore hardware accessories so I'll defer to his judgement on this one. My BB is still working fine after many years and he has nothing to prove here as far as I'm concerned. Case closed.

Yeah my Dad's pretty cool!

[Noizer]

But that's completely besides the point. The basic program proposed in the PRG has one function only, play square waves of various frequencies and it does it magnificently. Where that thread turned to samples and DAC, it was no longer about what the OP tried to discuss.

That thread is titled "User Port Sound" so the discussion fits in that frame

...
I remember using the MC1408 circuit to create a low frequency arbitrary signal generator. Using a few lines of BASIC I created a 256 byte table of values and I made the VIC cycle through it and output the values through the MC1408.

I also used this DAC to adjust the output voltage of a LM317 regulator. A few lines of BASIC to ask for the voltage and calculate the 8 bit value and I had a programmable power supply.

Very interesting, but have you ever tried doing these things in machine language rather than basic?

[Gyro Gearloose]

Very interesting, but have you ever tried doing these things in machine language rather than basic?

It was 25 years ago but I definitely remember that the loop for the function generator was in ML, otherwise it would have been glacial.

For sure the code that created the table of values is much easier in BASIC.

I enjoyed making the stupidest formulas possible, like (SIN / TAN ^ 2 * COS / pi)

etc

Just to see what is the craziest waveform I could show on the oscilloscope. The novelty wore off quickly however. It was too slow.

Reading 256 values from RAM and sending them out, I guess, would be what, 4 cycles for a LDA, 4 cycles for a STA, so 1MHz/8 = 125000 I/Os per second, and 256 values for a full cycle would give about 490Hz as the maximum frequency, but I guess you could improve that by unrolling the loop and using immediate mode LDA # and save two cycles that way, but I don't think I did that. It's also hard to get rid of the blip when the CPU has to jump back to the beginning instead of sending out a byte. Not clean.

490Hz fits with my recollection. Of course you can increase the frequency by reducing the time resolution of the table, maybe fit 2 to 4 cycles in there.

The voltage regulator would not benefit in the slightest from ML, just calculating a value and POKEing it to get the voltage doesn't need speed. At all.

My teachers didn't know what to make of me with my hand-painted zebra-striped VIC-20, but the coursework never specified I had to use the school's computers... My stuff worked and I passed the courses.